We propose to isolate and identify the toxins produced by algae of both marine and freshwater environments. Environmental conditions for maximal algal growth will be determined to assure sufficient material for continuous chemical investigation. The effects of environmental factors on toxin production will be investigated. In those frequent instances were several toxins are produced by an alga, the biosynthetic mechanisms influencing the relative amounts of the toxins will be examined. Comparisons will be made between toxic and non-toxic strains of selected algal species. The algal toxins will be isolated and characterized as pure chemical compounds at Berkely. They will be subjected to structural investigations and synthesis. Knowledge gained in these studies will be applied to divising sensitive chemical assays for the toxins. Sensitive chemical assays will permit rapid and frequent environmental monitoring, thus providing a greater safety factor for the utilization of marine food resources when warranted. The chemical studies will allow for the possibility of divising antidotes, for studying the mechanism of toxic action, and will provide clues for influencing toxin biosynthesis.